The Moon Missions Before Apollo: The History of NASA’s Pioneer, Ranger, and Surveyor Programs by Charles River Editors

Author:Charles River Editors [Charles River Editors]
Language: eng
Format: epub
Publisher: Charles River Editors
Published: 2020-07-22T16:00:00+00:00

Chapter 9: After Ranger

The images obtained by the last three Ranger spacecraft were very helpful, but they didn’t actually answer some fundamental questions. The Ranger images showed what appeared to be large, flat, boulder and crater-free areas. It was tempting to believe that these might provide safe landing areas but they might simply be deep layers of dust into which a landing spacecraft would sink too deeply to be able to take-off again. The only way to be certain was a series on unmanned missions that would involve actual soft landings on the lunar surface.

In 1960, before the first Ranger spacecraft had even left the launch-pad, work had begun on a new program called Surveyor. This would place a series of unmanned landers on the lunar surface, proving once and for all whether a manned manding could be safely undertaken. Once again, this program was overseen by NASA with much of the detailed design work being undertaken by JPL (by this time, JPL was wholly owned by NASA, though still managed by CalTech University).

There were three main goals for the Surveyor Program:

•​ To prove that the lunar surface was a place where a landing could safely be made,

•​ To show that a spacecraft could reliably be launched from Earth and reach a defined destination on the moon (given that several of the Ranger spacecraft had missed the moon entirely, this was a major consideration),

•​ To prove that guidance and descent systems could reliably and safely land a spacecraft on the surface of the moon.

One of the things that had been learned from the Ranger Program was that, to improve chances of success, mission objectives should be kept as simple as possible. For example, the first Surveyor missions were originally designed to orbit the moon before landing. Experience gained in the Ranger Program led to this being changed. Surveyor craft would take-off from Earth, fly directly to the moon and then immediately descend and land in the designated area.

The launch vehicle used to get the Surveyor craft off Earth and to the moon was also modified from equipment first designed for Ranger. The first stage was a modified version of Atlas D called the LV-3C. This was an improved version of the first-stage Atlas rocket used in the Ranger Program coupled to a completely new second stage, the Centaur, the first American rocket to use liquid oxygen (LOX) and liquid hydrogen (LH2).

However, the Surveyor Program, just like Ranger, ran into all kinds of problems as scientists and engineers struggled to deal with new challenges. The first problems emerged during development and testing of the Atlas-Centaur combination by the main contractor, the Convair division of General Dynamics. The first test launch of the Atlas-Centaur took place in May 1962, less than one month after the unsuccessful Ranger 4 mission. The rocket took off but exploded and was destroyed less than one minute after leaving the launch pad. In all, there were seven test launches of the Atlas-Centaur, but only two were successful.

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